Hydraulic tappet



J; W. HUMPHREYS HYDRAULIC TAPPET March 12, 1957 Filed Oct. 19, 1955 a; fluwrgiz F BY I UM ATTORNESX/ l I l l l 1 IL United States Patent HYDRAULIC TAPPET John W. Humphreys Muskegon, Mich., assignor to Johnson Products, Inc., Muskegon, Mich., a corporation of Michigan Application October 19, 1955, Serial No. 541,387

7 Claims. (Cl. 123 -90) This invention is directed to a-novel, and very practical hydraulic tappet structure for use in internal combustion engines which, by reason of its novel structure, eliminates the need now present in substantially all hydraulic tappets of machining to very close tolerances with attendant expense. Of even more importance, an elimination is attained of measuring and sorting the tappet bodies and the plungers therewithin in hydraulic tappets, in incre ments of 33 or 50 millionths of an inch, for assembly of matching sorted bodies and plungers in their proper sizes, to keep the leakage of oil past the plunger to a proper limited amount, thereby preventing a noisy tappet upon reaching a high temperature, and further providing a correct fit of the matching parts which assures a reasonably long life of service of the tappet.

Withmy invention no sorting of bodies and plungers to fit therewithin is required. The tolerances concerning the dimensions of inner bores of the bodies and outer surfaces of the plungers may be relatively large and vary from .001 to .004", which tolerances permit quantity machining within such .003 variation in fitting. The relatively wide tolerances over what is now requiredin machining, and the elimination of measuring each body. and each plunger and of sorting and fitting greatly re duces the cost of manufacture to an extent reaching ap proximately ten percent of the total cost of the tappet.

An understanding of the novel structure embodying my invention in its preferred form may be understood from the following description, taken in connection with the accompanying drawing, in which,

Fig. l is an upper end or plan view of the hydraulic tappet.

Fig. 2 is a central longitudinal vertical section therethrough on the plane of line II-II of Fig. 1.

.Fig. 3 is a transverse horizontal section substantially on the plane of line III-III of Fig. 2, and

' Fig. 4 is an enlarged fragmentary vertical section on the same plane as Fig. 2, a fragmentary portion, such as Within the indicated circle IV, being shown enlarged.

Like reference characters refer to like parts in the different figures of the drawing.

In the construction illustrated the usual tappet body 1 of cylindrical form is bored downwardly from its upper end toward but short of the lower end which is closed, the under side of the lower end in use bearing against a cam on a camshaft of an internal combustion engine.

The plunger in the present invention includes an inner lower part 2 and an outer upper part 3 above it, the lower parting being inserted into the bore of the body and hav ing a relatively loose fit as compared to the usual hydraulic tappet fit in which the tolerances are as above stated. The upper body part 3 can be even still looser without materially affecting the operation, although in actual practice it is fitted about the same as the lower part 2.

Such plunger is normally retained within the body against moving out and disconnecting therefrom by a spring retainer 4 above the upper end of the upper part 3 which snaps into an annular groove 5 at the inner side 2,784,706 n sdMar- ;,1957

. r 2 a of the walls of the tappet body 1, in the usual much used way that the plungers of hydraulic tappets when assembled are thus kept from separation in packing, handling and shipping.

The inner and lower member 2 of the plunger is interiorly bored from its upper end downwardly to provide an oil supply chamber 6 which has an outlet througha reduced lower end passage 7 from'the lower end of the chamber 6 to the lower end'of a projecting nipple 8 at the lower end of the member 2. Such passage is normally closed by a flat, thin metal disk valve 9 held against the lower end of the nipple 8 by a light strength coiled compression spring 10 within a .cage 11 which .has an Opening at its lower end and through its side. The cage comes against the lower side ofthe member 2 atthe upper end of the cage and is held snugly in position by a coiled compression spring 12 of much heavier strength than the spring 10, seated at its lower end against the bottom of the tappet bore. The chamber 13 below the plunger member 2, in which the valve spring and cage are located, is the pressure chamber of the hydraulic tappet. Such valve structure, including the disk valve, springs 10 and 12 and the cage' 11, is old and wellknown and has been used in hydraulic tappets fora considerable time. r

At the upper end of the lower plunger member .2. a portion is cut away around the .outer side thereof making an annular upwardly and inwardly inclined surface 14, the member 2 at its upper end terminating in a narrowed annular lip 15 as shown in Figs. 2 and 4.

Between the upper end of the member 2 and the lower end of plunger member 3 a thin metallic disk 16 is placed:

having a downwardly and outwardly inclined annular flange 17. The peripheral edges of said flange come against the inner sides of the walls of the tappet body and are located outwardly from the. annular surface 14 of the member 2 a distance so that, as best? shown in. Fig. 4, an annular chamber 18 isrnadewhich maygbe,

filled with oil or other hydraulic liquid used, forced up- Wardly from the pressure chamber 13 between the lower member 2 and the walls of the body 1 to the chamber 18.

Preferably at the center of the disk 16 a circular opening 19 is made. I and inwardly from its integral'junction with the flange 17 a small opening 20 is pierced whichjis disposedso that, at its lower end, it' -is in. partial communication with the chamber 18, the major portion .of the l ower end of the opening or passage 20 being over the annular rim or lip 15 of the lower plunger member 2ni Such small pierced hole in practice projects over the edge,of

the upper annular rim 15 of themember 2 in an amount As an equivalent;

whichmay vary from .002 to .0055. the same effects and results maybe obtained by making a small hole, the area of which would be substantially that of the connecting passage between chamber 18 and the opening 20, through the flange 17. This however, because of the smallness of the hole made through the flange 17 would be a very diflicult and expensive operation and one not practical for high quantity production. The diameter of hole 20 is somewhat greater than the thickness of the disk, making it practical to pierce the hole during the fabrication of the disk.

An annular oil receiving groove 21 is made around the upper plunger member 3. It receives oil from the lubricating system of an internal combustion engine in the usual manner of all hydraulic tappets through the passage 22 in the body 1 being in registration. with the groove 21. From such groove 21 oil flows through a passage 23 leading to and over the opening 19 in the thin stamped disk 16. All that is necessary is that there shall be this free communication for flow of oil passing through the inlet at 22 so as to reach the oil supply chamber 6 of Also adjacent an edge of the disk 16.

- emos 3 the tappet. Thus while the opening 19 is preferably centrally disposed it is notnecessarily so.

With the structure as described the operation of the tappets is the same as with all hydraulic tappets except the metered movement of oil from the pressure chamber upward between thev piston plunger and the walls of the body 1 is not controlled by a sorted and selected assembly of the tappet bodies and tappet plungers held within limits considerably less than one-tenth of one-thousandths of an inch. But the oil under the pressure to which the oil in the chamber 13 is subjected may flow much more freely upward and fill the annular chamber 18 and then is restricted, or metered, in its flow through the narrowed small area connection .between such chamber 18 and the opening 20 to come against the under side of the upper plunger member 3. The flange '17 riding against the walls of the tappet .body substantially prevents flow of oil from the chamber 18 around the outer edges of said annular flange 17 in an upward direction.

The lower side of the upper plunger member 3 is machined flat so as to lie snugly against the upper side of the thin metal disk member 16. When on the down stroke of the tappet with the engine valve moving toward closed position, such valve reaches its closed position and the force of the engine valve spring is, for a very short, practically instantaneous time, removed from the upper member 3, the pressure of oil within the chamber 18 transmitted through the opening 20 against the under side of the upper member 3 will, for an instant, lift such member 3. This permits a small or metered quantity of oil to pass between the upper plunger member 3 and the disk 16 in the required amount of leakage necessary for the operation of hydraulic tappets; which, heretofore, has been the leakage from the pressure chamber 13, in very small amounts, because of the close fit of the plunger in the tappet body, only a very small or metered amount passing between such tappet body walls and the plunger.

In the practical operations and tests of the tappet it has been found that while the use of the opening at 20 through the disk 16 with the very small area communication between it and the annular chamber 18 is the most desirable structure from a practical standpoint, both in manufacture and use, the tappet still is operative, though perhaps with a less measure of success, if the hole 20 is eliminated and the edges of the flanges 17 merely rounded or at least reduced in contacting area below that shown in Fig. 4 so that a small and metered quantity of oil will pass between the bearing edges of said flanges and the walls of the tappet body against which they ride.

is not to be limited other than as required by the claims appended hereto which define the invention.

I claim:

1. A hydraulic tappet plunger adapted to be assembled within a tappet body .comprising, a lower plunger member having a liquid supply chamber, open at its upper end, and

My invention, while disclosed in the best form known to me,

a valve controlled outlet at its lower end, a thin metal disk over the upper open end of said member having edge portions adapted to bear against the inner sides of the walls of a tappet body in which said plunger is installed, and an upper plunger member having a flat lower side against the upper side of said disk.

2. Structure as defined in claim 1, said disk at its peripheral edge portions having a downwardly and outwardly extending annular flange integral therewith.

3. A hydraulic tappet plunger for assembly within a tappet body comprising, upper and lower plunger members, and a thin metal disk between adjacent ends of said members, the peripheral edges of which extend slightly beyond the outer sides of said members, the lower member having a liquid receiving chamber open at the upper end of said lower member and having a valve controlled outlet at the lower end thereof, said disk being located over the upper open end of said chamber, said disk having an opening therethrough at the upper end of said chamber, and said upper member having a liquid carrying passage from its outer side to and in conjunction with said opening in said disk.

4. In a hydraulic tappet having an elongated, interiorly bored body closed at its lower end and open at the upper end, the improvement comprising, a plunger within the body having a lower member normally spring forced outwardly, an upper member aligned with said lower mern;

ber, a thin disk between said members having peripheral edges in contact engagement with said body, said members and disk having passages therethrough in conjunction with each other for liquid passage, and said lower member having a valve normally closing the passage therethrough at the lower end thereof.

5. A hydraulic tappet having the elements in combination defined in claim 4, said disk at its peripheral portions having an annular flange inclined to the plane of said disk toward the closed end of said body, and said lower plunger member at its outer end portion having a reduced exterior diameter, thereby providing an annular chamber betweeen said flange and the outer end of said lower plunger member.

6. A hydraulic tappet plunger comprising, upper and lower plunger members, a thin disk between. adjacent ends of said members, said disk at its peripheral portions having a downwardly and outwardly inclined annular flange, and the adjacent upper end portion of said lower plunger member being reduced in diameter thereby providing an annular chamber between said flange and upper end of said lower plunger member, said disk having an opening therethrough in conjunction with said annular chamber.

7. Structure as defined in claim 6, said opening in said disk being located partly over the upper end of said lower plunger member, and partly over said chamber.

No references cited. 

